The U.S. military drawdown in Afghanistan is adding an unexpected toll on Americans as poppy production in that country reaches an all-time high, fueling a global opium and heroin scourge that also is funding terrorist activities, the Washington Times reported.

U.S. taxpayers have spent $7.5 billion over the past 12 years on counternarcotics efforts inside Afghanistan, but the withdrawal of troops has prompted a massive surge in the drug trade, America's top watchdog inside the country warned in a report Wednesday.

The narcotics situation in Afghanistan "is dire with little prospect for improvement in 2014 or beyond," said John Sopko, special inspector general for Afghanistan reconstruction.

Mr. Sopko's assessment is shared by the U.S. Drug Enforcement Administration, the United Nations and other global agencies. Afghanistan produces roughly 90 percent of the world's illicit opium, according to the State Department.

"As we approach 2014 and the withdrawal of international forces from the country, the results of the Afghanistan Opium Survey 2013 should be taken for what they are - a warning, and an urgent call to action," said Yury Fedotov, executive director of the United Nations Office on Drugs and Crime.

The latest data from the U.N. office show that approximately 516,000 acres of land in Afghanistan are under opium poppy cultivation, an all-time high and a 36 percent increase since 2012.

U.S. officials blame the surge in Afghan opium on the withdrawal of American troops, many of whom led the counternarcotics effort of the past decade.

The Department of Defense and the Counter Narcotics Police of Afghanistan told the special inspector general that the drawdown of coalition forces in Afghanistan has hurt counternarcotics efforts, especially in the southern provinces of Helmand and Kandahar where poppy growing is at its highest. Those provinces were the focus of a surge of coalition forces and their subsequent withdrawal.

The special inspector general reports that there are more than 74,000 acres of poppy fields in Helmand province alone.

Over the past several years, eradication efforts seemed to have made hardly a dent. According to the report, since 2008, eradication efforts have affected on average less than 4 percent of the annual national poppy crop.

The numbers are likely to fall further this year as the poppy-growing cycle and eradication efforts coincide with Afghan elections, taking forces away to help with security at the polls.

The rise in opium trafficking and production is alarming to U.S. officials, but not for the reasons many might suspect. American heroin use is rising, but that supply comes mostly from South America and not Afghanistan. The real concern for U.S. officials is that the booming Afghan opium trade - mostly with Europe - is enriching warlords, the Taliban and Islamic extremists and helping fund terrorist activity.

The DEA said many high-ranking members of the Taliban are also major opium kingpins and that terrorist attacks often are funded by drug sales.

In July 2005, several suicide bus bombings in central London killed 52 people. DEA spokesman Rusty Payne said these terrorist attacks were funded by the sale of hashish.

"The drugs may never touch the U.S., but the dollars that are raised from the trafficking and the sale of these things are going back to Hezbollah and al Qaeda, people that don't like us very much," Mr. Payne said. "They have operatives all over the world, even here. These are organizations that need money to operate."